These are 25 of the happiest cities in the U.S., study says

These are 25 of the happiest cities in the U.S., study says

Regular dental checkups and vacation time may not seem related, but according to a survey measuring happiness in U.S. cities, they are both good indicators of overall well-being.

A study compiled by National Geographic, author Dan Buettner and Gallup used 15 factors that also include quality of diet, financial security, and daily learning, among others. The findings are based on 250,000 interviews done across the country from 2014 to 2015 as part of the National Geographic Gallup Special/Blue Zones Index.

Boulder, Colorado toped the list thanks to its proximity to nature, a strong feeling of community, a largely active lifestyle and sustainable development, among other qualities.